Laser sorting method can improve pepper seed quality

USAK, Turkey – The high cost of vegetable crop seeds – especially hybrids – has led producers to seek out new precision seeding and transplant production systems. The quality of vegetable seed lots can be affected by a variety of prestorage and poststorage factors, so finding ways to improve seedling emergence percentages and uniformity is critically important.

Chlorophyll fluorescence (CF) can be used successfully to improve quality in capsicum pepper seed lots, according to research from the University of Usak, the University of Ankara and Wageningen UR Greenhouse Horticulture.

Peppers (Capsicum annuum L.) have a habit of nonsynchronous seed production, which means that pepper fruits produced from different flowering times mature at different periods, thus resulting in seeds of varying maturity and quality. This wide variation in a single lot can reduce overall seed quality, the researchers found. “Less-mature seeds germinate more slowly and produce smaller seedlings, whereas mature seeds emerge faster and produce larger seedlings,” the researchers wrote in a recent HortScience paper. “This variation in seed maturity ultimately results in variations in plant growth and development.”

They set out to find a way to separate out less-mature seeds to enhance the overall quality of pepper seed lots using CF, which has been used successfully to detect and sort other types of seeds. The nondestructive technique uses laser technology, narrow optical bandwidth filters and detection of chlorophyll in the seed coat to measure the resulting CF and link it with the quality of the seeds. The technique has been found to be effective for sorting cabbage, tomato, barley, carrot and pepper seeds.

“While previous studies evaluated seed quality solely based on laboratory germination tests conducted under optimum germination conditions, our work tested the effect of CF sorting not only on laboratory germination, but also on emergence and physiological aging as indicators of seed vigor,” said Burcu Begüm Kenanoglu of the University of Usak. “The results showed that CF sorting affects germination and seed vigor. In our work, CF worked on the four cultivars examined, and this shows that the method may be well suited for Capsicum annuum. Chlorophyll fluorescence has the potential to upgrade seed quality in pepper lots as a nondestructive sorting technology.”